Medical systems, devices, and related methods

ABSTRACT

In one example, a medical system may comprise a delivery tube configured to couple to a vacuum source and provide negative pressure to a distal portion of the delivery tube; and a porous body at a distal portion of the delivery tube, the porous body including a first section and a second section removable from the first section.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority from U.S. ProvisionalApplication No. 62/982,926, filed on Feb. 28, 2020, which isincorporated by reference herein in its entirety.

TECHNICAL FIELD

This disclosure generally relates to medical systems, devices, andrelated methods that may be used to treat a subject. Aspects of thedisclosure relate to medical systems, devices, and methods forendoscopic medical procedures, such as applying negative pressure totissue for wound treatment.

BACKGROUND

Endoscopic and open surgical procedures of the gastrointestinal (GI)tract include, for example, colonic resection, bariatric surgery,esophagectomy, gastric bypass, and sleeve gastrectomy, among others.These procedures may result in perforation, post-surgical leaks, orother wounds of the tract. Limited treatment options exist for managingsuch wounds, which have significant morbidity and mortality rates.Options include surgical re-operation and endoscopic placement of astent or clips. Surgery is relatively invasive and also has highmorbidity and mortality rates. Endoscopic stent placement is a lessinvasive option. The placed stent, however, can migrate from theintended location and/or wall off infection at the treatment site,inhibiting drainage.

The systems, devices, and methods of this disclosure may rectify some ofthe deficiencies described above or address other aspects of the art.

SUMMARY

Examples of the disclosure relate to, among other things, systems,devices, and methods for performing one or more medical procedures withthe medical systems and devices. Each of the examples disclosed hereinmay include one or more of the features described in connection with anyof the other disclosed examples.

In one example, a medical system may comprise a delivery tube configuredto couple to a vacuum source and provide negative pressure to a distalportion of the delivery tube; and a porous body at a distal portion ofthe delivery tube, the porous body including a first section and asecond section removable from the first section.

In other aspects of the disclosure, the medical system may include oneor more of the features below. The second section may extendcircumferentially around a radially-outermost surface of the firstsection, and the radially-outermost surface may be radially-outermostfrom a central longitudinal axis of the porous body. The system mayfurther comprise a string coupled to the second section and extendingfrom the porous body to a proximal portion of the delivery tube. Theporous body may further comprise a third section extendingcircumferentially around a radially-outermost surface of the secondsection, and the radially-outermost surface of the second section may beradially-outermost from a central longitudinal axis of the porous body.The system may further comprise a first string coupled to the secondsection and extending from the porous body to a proximal portion of thedelivery tube; and a second string coupled to the third section andextending from the porous body to the proximal portion of the deliverytube. The delivery tube may be coupled to a vacuum source, the porousbody may be cylindrical, and a central longitudinal axis of the porousbody may be longitudinally aligned with a central longitudinal axis ofthe delivery tube. The system may further comprise a flexible overtubecoupled to the second section, and the delivery tube may extend througha lumen of the flexible overtube.

In other aspects of the disclosure, the medical system may include oneor more of the features below. The first section may be cylindrical andthe second section may wrap around the first section. The first sectionand the second section may be separated by perforations. The firstsection may be cylindrical and may include a central longitudinal axis;the second section may extend circumferentially around aradially-outermost surface of the first section, the radially-outermostsurface may be radially-outermost from the central longitudinal axis ofthe first section; and the second section may be cylindrical and includea lumen extending through the central longitudinal axis configured toreceive the first section. A layer of mesh, adhesive, or agent may bepositioned between the first section and the second section. The systemmay further comprise a cylindrical overtube extending around thedelivery tube and the porous body, and the overtube may be configured tocover the porous body and the delivery tube. The system may furthercomprise a string coupled to the second section and the third section,the string may extend from the sponge to a proximal portion of thedelivery tube, and wherein the string includes: a first portion coupledto the second section and the third section, wherein the first portionhas a length longer than a length of the delivery tube; and a secondportion coupled to the third section and extending proximally to theproximal portion of delivery tube. The first section, the secondsection, and the third section may be concentric and may have differentthicknesses measured orthogonal to a central longitudinal axis of theporous body. The first string may be a different color than the secondstring.

In another aspect, a medical device may comprise a porous body includingat least one perforation; a negative pressure conduit having an openingformed therein that is in fluid communication with the porous body,wherein the negative pressure conduit is configured to apply a negativepressure to the porous body; and a string coupled to the porous body andextending from the porous body to a proximal portion of the conduit. Theporous body may be configured to separate into separate sections whenthe string is pulled proximally.

In other aspects of the disclosure, the device may include one or moreof the features below. The at least one perforation may extendlongitudinally along the porous body. The conduit may be longitudinallyaligned with a central cylindrical section of the porous body, and theat least one perforation may extend parallel to a longitudinal axis ofthe central section. The at least one perforation may include a firstperforation and a second perforation; and the first perforation may becloser to a central longitudinal axis of the porous body than the secondperforation.

In another aspect, a method of performing a medical procedure maycomprise: positioning a porous body adjacent to tissue of a target site;applying a negative pressure to the porous body; and pulling a stringcoupled to the porous body proximally to remove a first section of theporous body while a second section of the porous body remains positionedat the target site.

It may be understood that both the foregoing general description and thefollowing detailed description are exemplary and explanatory only andare not restrictive of this disclosure, as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate exemplary aspects of thedisclosure and together with the description, serve to explain theprinciples of the disclosure.

FIG. 1 illustrates a perspective view of a distal portion of anexemplary medical device, according to aspects of this disclosure.

FIG. 2 illustrates a perspective view of a distal portion of anexemplary medical device, according to aspects of this disclosure.

FIG. 3 illustrates a perspective view of a distal portion of anexemplary medical device, according to aspects of this disclosure.

FIGS. 4A-4D illustrate views of a medical device in various stages ofusage in a subject, according to aspects of the disclosure.

DETAILED DESCRIPTION

The terms “proximal” and “distal” are used herein to refer to therelative positions of the components of an exemplary medical system andexemplary medical devices. When used herein, “proximal” refers to aposition relatively closer to the exterior of the body or closer to amedical professional using the medical system or medical device. Incontrast, “distal” refers to a position relatively further away from themedical professional using the medical system or medical device, orcloser to the interior of the body. Proximal and distal directions arelabeled with arrows marked “P” and “D”, respectively, throughout thefigures. As used herein, the terms “comprises,” “comprising,” “having,”“including,” or other variations thereof, are intended to cover anon-exclusive inclusion, such that a system, device, or method thatcomprises a list of elements does not include only those elements, butmay include other elements not expressly listed or inherent thereto.Unless stated otherwise, the term “exemplary” is used in the sense of“example” rather than “ideal.” As used herein, the terms “about,”“substantially,” and “approximately,” indicate a range of values within+/−10% of a stated value.

Endoluminal vacuum therapy (EVAC) has been proposed. In EVAC, negativepressure is delivered to the wound site in the GI tract, for examplethrough a nasogastric tube having a sponge at its terminal end. Thesponge is placed endoscopically into the perforation, leak, or otherwound. Negative pressure then is applied. Devices and systems suited forEVAC are limited, however.

Embodiments of this disclosure include devices, systems, and methods forendoluminal vacuum therapy (EVAC). In examples, EVAC includesendoluminal placement of a sponge or other like material into the woundsite, including a perforation, cyst, a leak, an anastomosis, etc.Placement of the material may be via a catheter, scope (endoscope,bronchoscope, colonoscope, gastroscope, duodenoscope, etc.), tube, orsheath, inserted into the GI tract via a natural orifice. The orificecan be, for example, the nose, mouth, or anus, and the placement can bein any portion of the GI tract, including the esophagus, stomach,duodenum, large intestine, or small intestine. Placement also can be inother organs reachable via the GI tract.

Reference will now be made in detail to examples of this disclosuredescribed above and illustrated in the accompanying drawings. Whereverpossible, the same reference numbers will be used throughout thedrawings to refer to the same or like parts.

FIG. 1 illustrates a perspective view of an exemplary medical device 100including a sponge 102, that may be used to help the healing of aninternal wound, anastomosis, or the like, in a subject. Sponge 102 maybe substantially cylindrical and may be attachable, e.g., coupled, to avacuum tube 104. A central longitudinal axis A of sponge 105 may bealigned with a central longitudinal axis (also shown as axis A in FIG. 1) of vacuum tube 104. Sponge 102 may be sized in accordance with apatient's anatomy and may include a lumen or recess (not shown) toreceive vacuum tube 104. The recess may be in a proximal end of sponge102. In some examples, sponge 102 may include a curved,radially-outermost surface 119. Sponge 105 may be flexible andconfigured to move through tortuous pathways of body lumens of apatient.

Sponge 102 may include a plurality of concentric sections 116, 114, 112,110, 108. Each section 116, 114, 112, 110, 108 may be separate from eachother section 116, 114, 112, 110, 108. A central section 116 may beshaped as a cylinder and may be directly coupled to vacuum tube 104. Forexample, section 116 may have a lesser length than sections 114, 112,110, and 108, to accommodate a distal portion of tube 104 within sponge102. Each of the other sections 114, 112, 110, 108 may extendcircumferentially around the central section 116 forming concentric,ring-like cylindrical sections 114, 112, 110, 108 that are nested withinone another. In some examples, each section 116, 114, 112, 110, 108 ofsponge 102 may be a different distance from central longitudinal axis A,and each section 116, 114, 112, 110, 108 may extend longitudinally inthe direction of central longitudinal axis A. In some examples, sections116, 114, 112, 110, 108 may have the same thickness measured in adirection perpendicular to longitudinal axis A, and sections 114, 112,110, 108 may have the same length measured parallel to longitudinal axisA. In other examples, sections 116, 114, 112, 110, 108 may havedifferent thicknesses and/or may have different lengths. In someexamples, sponge 102 may include five sections (shown in FIG. 1 ), andin other examples, sponge 102 may include 2, 3, 4, 6, 7, 8, 9, or anyother suitable number of sections. Each section 114, 112, 110, 108 maycontact the radially-outer surface from longitudinal axis A of theadjacent section 116, 114, 112, 110, respectively.

Sections 116, 114, 112, 110, 108 may be configured to move relative toeach other such that a section 116, 114, 112, 110, 108 may be moved inthe proximal-distal direction relative to the other sections 116, 114,112, 110, 108 with no or minimal movement of the other sections 116,114, 112, 110, 108. In some examples, a layer of mesh, adhesive, oragent may be positioned between each section 116, 114, 112, 110, 108 andthe adjacent section 116, 114, 112, 110, 108, which may facilitateremoval of each section 116, 114, 112, 110, 108. In other examples, anyother suitable material, capable of coupling adjacent sections togetheryet permitting them to release from one another upon a suitable force,may be used between adjacent sections. Such materials can include asuitable adhesive layer sandwiched between adjacent sections. In someexamples, a medicament may be layered/sandwiched between adjacentsections and may be configured to release from sponge 102 when theradially-outer layer from the longitudinal axis of sponge 102 is removedand exposes the layer of medicament. In some examples, sponge 102 may besized to fill a wound region 450 with a radius of between approximately1 cm and 7 cm, and/or a wound region 450 with a depth of betweenapproximately 1 cm and 7 cm.

In embodiments of this disclosure, sponge 102 may be any suitablebiocompatible material that may absorb liquids and/or permit liquid topass therethrough via negative pressure. The material may be flexible,compressible, porous, hydrophilic, sterile, biodegradable, and/ordisposable. The sponge material may be an open-cell foam having poresand channels therein. Suitable materials include polyurethanes, esters,ethers, composite materials, and any medical-grade material.

A string or suture 106 may be coupled to sponge 102 and may extend fromsponge 102 proximally to a proximal portion of medical device 100.String 106 may be coupled to each section 108, 110, 112, 114 exceptcentral section 116. A length of string 106 longer than the length(measured longitudinally) of medical device 100 may be between eachpoint at which string 106 is coupled to each section 108, 110, 112, 114,which may allow each section 108, 110, 112, 114 to be pulled proximallythe entire length of medical device 100 without pulling any othersection 108, 110, 112, 114. The length of string 106 between each pointof string 106 that is coupled to each section 108, 110, 112, 114 may besandwiched between adjacent sections 108, 110, 112, 114. For example,string 106 may be coupled to section 108, then coupled to section 110,then coupled to section 112, and then coupled to section 114; and thelength of string between each point at which string 106 is coupled toeach section may be positioned between sections (such as wound around asection, etc.). This additional length of string 106 between eachsection 108, 110, 112, 114 is configured to allow the user to pullsection 108 proximally out of a patient's body without removing the restof sections 110, 112, 114, 116; and then proceed to pull the nextradially-outermost section (in this case, section 110) proximally out ofa patient's body without moving the rest of sections 112, 114, 116; andso forth.

In some examples, medical device 100 may include a single, separatestring coupled to each section 108, 110, 112, 114; and thus four strings106 would extend proximally from sponge 102. In some examples, medicaldevice 100 may include a single string 106 coupled to each section 108,110, 112, 114, and each of the strings 106 may be a different color sothe user removing the layers (sections 108, 110, 112, 114) of sponge 102may identify which layer is being removed. In other examples, string 106may be replaced with a wire, a tether, or an extrusion. In someexamples, string 106 may be replaced with a series of concentric tubesextending from sponge 102 to a proximal portion of medical device 100,with each tube coupled to a single section 108, 110, 112, 114. In thisexample, the tubes would be flexible and configured to move through apatient's body.

Vacuum tube 104 may be cylindrical with a central lumen (not shown)extending along central longitudinal axis A of vacuum tube 104. Vacuumtube 104 may have a length and width configured to extend through aworking channel of an endoscope or other medical delivery device, andmay be flexible. In some examples, vacuum tube 104 may include one ormore holes at a distal portion of vacuum tube 104, including portionswithin sponge 102. Vacuum tube 104 may be coupled to a vacuum source 120at a proximal portion of vacuum tube 104. Vacuum source 120 may supplynegative air pressure to vacuum tube 101. Vacuum tube 104 may be coupledto at least central section 116 of sponge 102, and may supply negativeair pressure to sponge 102. In some examples, vacuum tube 104 may extendthrough central portion 116 of sponge 102. Vacuum tube 104 may bereceived within a recess of a proximal portion of sponge 102, and insome examples vacuum tube 104 may be coupled to sponge 102 via anadhesive, a suture, a thread, and/or other attachment means.

In some examples, medical device 100 may include an overtube (not shown)which may extend over vacuum tube 104 and sponge 102. The overtube maycompress sponge 102 such that the radially-outermost surface fromlongitudinal axis A of sponge 102 is smaller than when sponge 102 ispositioned outside of the overtube. An overtube may facilitate movementof medical device 100 through a working channel of an endoscope or othermedical device. In addition, an overtube may prevent unwanted contact ofsponge 102 with tissue of the patient.

FIG. 2 shows a perspective view of a distal portion of an alternativeembodiment of a medical device 200. Medical device 200 may have any ofthe features described hereinabove with regard to medical device 100.Medical device 200 may include a vacuum tube 204 and a sponge 202, andmay be coupled to a vacuum source 220 at a proximal portion of medicaldevice 200. In the same manner described hereinabove with regard tosponge 102, sponge 202 includes concentric, cylindrical sections 212,214, 216. At least central section 216 is directly coupled to vacuumtube 204, section 214 is coupled to a first string 223, and section 212is coupled to a second string 221. Each of first string 223 and secondstring 221 may extend from sponge 202 to a proximal portion of medicaldevice, and may be configured to be moved proximally to remove a section212, 214 of sponge 202 from a body of a patient. In some examples (shownin FIG. 2 ), strings 221, 223 may be coupled to each of sections 212,214, respectively, at a proximal portion of each section 212, 214.Strings 221, 223 may extend proximally outside of vacuum tube 204.

FIG. 3 shows a perspective view of a distal portion of anotherembodiment of a medical device 300. Medical device 300 may have any ofthe features described hereinabove with regard to medical devices 100,200. Medical device 300 may include a vacuum tube 304, a sponge 302, anda string 306. Vacuum tube 304 may be coupled to a vacuum source 320 at aproximal portion of vacuum tube 304. Sponge 302 may include severalsections 331, 332, 333, 334, 335, 336, and the sections 331, 332, 333,334, 335 may be coiled around central section 336. Each section 331,332, 333, 334, 335 may be wrapped around the section or sectionsadjacent to it and/or radially inward of it, and sections 331, 332, 333,334, 335, 336 may form a spiral about a central longitudinal axis ofsponge 302. In some examples, a single, rectangular sponge may beperforated to divide the sponge into sections 331, 332, 333, 334, 335,336, and then the rectangular sponge may be rolled around a centralsection (such as section 336 in FIG. 3 ) to form sponge 302. String 306may be coupled to each section 331, 332, 333, 334, 335, 336, withportions of string that are the length of medical device 300 betweeneach point of coupling string 306 to each respective section 331, 332,333, 334, 335, 336.

Adjacent sections 331, 332, 333, 334, 335, 336 may be separated byperforations 361, 362, 363, 364, 365. Perforations 361, 362, 363, 364,365 may be configured to allow sections 331, 332, 333, 334, 335, 336 toseparate from each other when a user pulls string 306 proximally. Forexample, when a user first pulls string 306 proximally, section 331 maybe pulled proximally and perforation 361 may allow section 331 toseparate from section 332 without moving or minimally moving section 332or any other section. The user may then continue to pull string 306proximally to separate section 332 from section 333, then separatesection 333 from section 334, etc. In other examples, individual strings306 may be coupled to each section 331, 332, 333, 334, 335, 336 suchthat a user needs to pull one string to remove section 331, then asecond string to remove section 332, etc. In some examples (not shown),central section 336 may be a separate sponge from sponge 302.Perforations 361, 362, 363, 364, 365 may extend longitudinally,substantially parallel to axis A. In other examples, perforations 361,362, 363, 364, 365 may be replaced by a thinner region or otherwiseweakened region between each section 331, 332, 333, 334, 335, 336,permitting release of adjacent sections 331, 332, 333, 334, 335, 336upon application of a suitable force. Each section 331, 332, 333, 334,335, 336 may be any suitable size. In some examples, each section 331,332, 333, 334, 335, 336 may extend 360° circumferentially around acentral longitudinal axis of vacuum tube 304. In other examples, eachsection 331, 332, 333, 334, 335, 336 may extend less than 360°circumferentially around the axis, like section 331 shown in FIG. 3 .Perforations 361, 362 may provide a means for a user to select the sizeof sponge 302 prior to insertion of sponge 302 into a body of a patient.Also, a layer of mesh, adhesive, agent, or other material can be usedbetween adjacent sections 331, 332, 333, 334, 335, 336, as describedhereinabove.

Reference will now be made in detail to methods of operating medicaldevices 100, 200, 300. Although FIGS. 4A-4D show the operation ofmedical device 100, any of the medical devices 100, 200, 300 may operateby the same method described herein below with regard to medical device100.

FIGS. 4A-4D show side views of medical device 100 in use within a bodylumen 452 of a patient (e.g. a portion of the gastrointestinal tract) totreat a wound region 450. To position medical device 100 at a woundregion 450 within a body of a patient, a user may insert an endoscope(or other medical device) into the patient and locate wound region 450by visualizing the wound region 450 using an image sensor (not shown) ata distal end of the endoscope. Once the endoscope is positionedproximate to wound region 450, the user may insert medical device 100into a working channel of the endoscope and move medical device 100distally through the working channel. In other examples, medical device100 may be positioned within a working channel proximate to the distalend of the endoscope prior to inserting the endoscope into the body ofthe patient. In some examples, an overtube may be positioned betweenmedical device 100 and a working channel, and the overtube may preventexcessive bending, twisting, or other shape distortion of medical device100 within the working channel while the user moves medical device 100distally through the working channel. In other examples, a user may notuse an endoscope and may insert medical device 100 into the body of thepatient directly and not within a working channel of a separate medicaldevice.

With a distal portion of the endoscope positioned proximate to woundregion 450, the user may move medical device 100 distally out of theworking channel and position sponge 102 within wound region 450. Theflexibility, compressibility, and shape of sponge 102, and theflexibility of vacuum tube 104 may facilitate maneuvering medical device100 within wound region 450. In some examples, sponge 102 may bend,twist, and/or change shape to conform to the shape of wound region 450.The user may then activate vacuum source 120 to supply negative pressureto sponge 102 through vacuum tube 104, which may pull portions of woundregion 450 towards sponge 102. Once medical device 100 is positionedwithin wound region 450 and vacuum pressure is supplied to sponge 102,the user may then leave sponge 102 and vacuum tube 104 positioned withinthe body of the patient for approximately 48-72 hours. The negativepressure applied to sponge 102 may also remove fluid and other materialfrom the wound region 450. In other examples, sponge 102 may be leftwithin the patient's body for any other period of time. Vacuum tube 104may remain within the body of the patient during treatment, and mayextend out of the patient to vacuum source 120 through the patient'srectum, mouth, nose, other bodily orifice, or other opening in thepatient's body such as an incision, etc. In some examples, an overtubemay also remain within the patient's body during treatment and may covera portion of sponge 102 outside of the wound region 450.

As wound region 450 heals, wound region 450 may shrink and becomesmaller. When a user would like to remove a section of sponge 102 (suchas after 48-72 hours has passed since the initial positioning of sponge102 within wound region), the user may first disconnect vacuum tube 104from vacuum source 120 and supply saline 460 to vacuum tube 104 in orderto deliver saline 460 to wound region 450. FIG. 4B illustrates saline460 deployed within wound region 450. Although saline 460 is shown inFIG. 4B, any suitable liquid known in the art may be used to fill woundregion 450 to facilitate removal of portions of sponge 102. Saline 460may facilitate release of sponge 102 from the walls of wound region 450.Once saline 460 is deployed, a user may position a rigid tool 455 withinthe patient such that a distal end of rigid tool 455 is contactingsection 110 of sponge 102. Rigid tool 455 may prevent proximal movementof section 110 when the user pulls section 108 proximally. Rigid tool455 may be a metal wire, tube, rod, or any other suitable relativelyrigid member.

After filling wound region 450 with saline 460 and positioning rigidtool 455 abutting section 110, the user may then pull string 106proximally to pull section 108 proximally and remove section 108 fromwound region 450. FIG. 4C shows section 108 being pulled proximally outof wound region 450, and rigid tool 455 contacting section 110 toprevent proximal movement of section 110. Although FIG. 4C shows the useof rigid tool 455, a user may just pull string 106 proximally to removesection 108 without the aid of a rigid tool 455. After section 108 hasbeen removed from the patient's body, the user may then reconnect andactivate vacuum source 120 to supply negative pressure to sponge 102,and tissue of wound region 450 may be pulled towards section 110 (shownin FIG. 4D). This may allow sponge 102 to consume less space withinwound region 450 and may also allow wound region 450 to continue todecrease in size as wound region 450 heals. The user may repeat thesesteps until central section 116 is fully exposed to wound region 450,and then the user may fully remove medical device 100 from the patientonce treatment is complete. Note central section 116 may be removed fromthe patient's body by pulling vacuum tube 104 proximally.

When treating tissue with any of the medical devices 100, 200, 300,described herein, it may be beneficial to remove portions of spongeafter a patient's tissue has developed scabbing or otherwise healed. Byremoving sections of a sponge 102, 202, 302, from the area of tissuewith scabbing and allowing a new section of sponge (or portion of spongethat has not yet contacted tissue for treatment) to engage tissue, thetissue may heal faster.

Although FIGS. 4A-4D illustrate sponge 100 being used to treat a woundregion within a patient's body, this disclosure is not so limited.Sponges 102, 202, 302 and the procedures discussed herein may be used totreat wounds, leaks, perforations, etc. in a subject's uppergastrointestinal tract, a subject's lower gastrointestinal tract, otherlumens or cavities within a subject, on an exterior of a subject, etc.Various aspects discussed herein may help to reduce recovery time,reduce physician interventions, reduce a need and/or reliance on imagingor visualization to position the sponge, reduce component costs, reducethe risks to the subject, etc.

Additionally, various aspects discussed herein may be packaged as a kitto be used to treat a subject.

While principles of the disclosure are described herein with referenceto illustrative aspects for particular applications, it should beunderstood that the disclosure is not limited thereto. Those havingordinary skill in the art and access to the teachings provided hereinwill recognize additional modifications, applications, aspects, andsubstitution of equivalents all fall within the scope of the aspectsdescribed herein. Accordingly, the disclosure is not to be considered aslimited by the foregoing description.

1-20. (canceled)
 21. A medical system comprising: a delivery tubeconfigured to couple to a vacuum source and provide negative pressure toa distal portion of the delivery tube; and a porous body at a distalportion of the delivery tube, the porous body including: a firstsection, a second section removable from the first section, and a thirdsection removable from the second section, wherein the first section isnested within the second section, and wherein the second section isnested within the third section.
 22. The medical system of claim 21,wherein the second section extends circumferentially around the firstsection, and wherein the third section extends circumferentially aroundthe second section.
 23. The medical system of claim 21, wherein thefirst section, the second section, and the third section are concentric.24. The medical system of claim 21, wherein the first section is coupledto the delivery tube.
 25. The medical system of claim 21, wherein thefirst section has a cylindrical shape.
 26. The medical system of claim21, wherein a length of the first section is shorter than lengths ofeach of the second and third sections.
 27. The medical system of claim21, wherein each of the first section, the second section, and the thirdsection has a different thickness measured orthogonally to a centrallongitudinal axis of the porous body.
 28. The medical system of claim21, further comprising a layer of one of an adhesive, a mesh, or anagent disposed between each of the first section and the second sectionand the second section and the third section.
 29. The medical system ofclaim 21, further comprising a string coupled to second section and thethird section.
 30. The medical system of claim 29, wherein the stringextends from the porous body to a proximal portion of the delivery tube,and wherein the string includes: a first portion coupled to the secondsection and the third section, wherein the first portion has a lengthlonger than a length of the delivery tube; and a second portion coupledto the third section and extending proximally to the proximal portion ofthe delivery tube.
 31. A medical system comprising: a delivery tubeconfigured to couple to a vacuum source and provide negative pressure toa distal portion of the delivery tube; and a porous body at a distalportion of the delivery tube, the porous body including: a firstsection, a second section extending circumferentially around the firstsection, and a third section extending circumferentially around thesecond section, wherein the first section is nested within the secondsection, and wherein the second section is nested within the thirdsection.
 32. The medical system of claim 31, wherein the first section,the second section, and the third section are concentric.
 33. Themedical system of claim 31, wherein the first section has a cylindricalshape.
 34. The medical system of claim 31, wherein each of the firstsection, the second section, and the third section extends 360°circumferentially around a central longitudinal axis of the deliverytube.
 35. The medical system of claim 31, wherein each of the firstsection, the second section, and the third section extends less than360° around a central longitudinal axis of the delivery tube.
 36. Themedical system of claim 31, wherein the second section is separated fromthe first section by a first perforation, and wherein the third sectionis separated from the second section by a second perforation.
 37. Themedical system of claim 31, wherein a length of the first section isshorter than lengths of each of the second and third sections.
 38. Themedical system of claim 31, further comprising a string coupled to thesecond section and the third section.
 39. A medical system comprising: adelivery tube configured to couple to a vacuum source and providenegative pressure to a distal portion of the delivery tube; and a porousbody at a distal portion of the delivery tube, the porous bodyincluding: a first section, the first section having a cylindricalshape, a second section extending circumferentially around the firstsection, and a third section extending circumferentially around thesecond section, wherein each of the first section, the second section,and the third section extends 360° circumferentially around a centrallongitudinal axis of the delivery tube.
 40. The medical system of claim39, wherein the first section, the second section, and the third sectionare concentric.